Gas and air mixing apparatus



March 31,. 1936. J, J. MAXON GAS AND AIR MIXING APPARATUS Filed July 5, 1933 2 Sheets-Sheet l ZJOHN JM XON ATTORNEY.

arch 31, 1936. J. J, MAXON 2,035,904

GAS AND AIR MIXING APPARATUS Filed July 5, 1935 2 sheets-sheet 2 INVENTOR.

ATTORNEY.

Patented Mar. 31, 1936 PATENT OFFICE 7 2,035,904 'GAs AND AIR- MIXING APPARATUS John J. Maxon, Muncie, Ind., assignor to Maxon Premix Burner Company, Muncie, Ind., a corporation of Delaware Application July 5, 1933, Serial No. 679,095

4 Claims.

This invention relates to improvements in apparatus wherein a complete mixture of combustible gas and air is obtained mechanically, and wherein a complete combustion of the mixture 5 begins immediately upon its passing from the burner conduit into the combustion chamber.

An apparatus of the above description, and as illustrated in United States Letters Patent issued April 9, 1918 to Harry R. Maxon, No. 1,262,078, 1 comprises a fan adapted and arranged to receive air at substantially atmospheric pressure, an unobstructed delivery conduit leading from the fan, a damper for regulating the quantity of air admitted to the fan casing, a pipe for supply of fuel 15 gas directly to the fan casing, and a valve for regulating the gas supply from said pipe.

In an apparatus of the above description, a characteristic of the operation of the fan is that there is variation in the suction force of the fan 20 coincidentally with variation of the area of the opening admitting air to the fan. Also it is a characteristic of the operation of furnaces that incident to peculiarities of form, nature and construction, and of draught, currents and pressures, 25 a fixed or unchanged ratio of gas and air in the fuel mixture is ineffective. In practice it has been ascertained that in the absence of means to modify the variation of inflow of gas, to compensate for the effect produced on the mixture by 30 the said change in suction force, and by conditions in the combustion chamber, there is an indefinite and inefficient proportioning of the air and gas.

Accordingly, my invention has for its object the 35 providing, in combination with the fan casing, of means consisting of a damper to vary the amount of air to be admitted, a valve to vary the amount of gas to be admitted, and means cooperating with the damper and the valve, 40 whereby a variation of the inflow of gas, with relation to the air inflow, and modification of the said variation may be automatically had and maintained at the different stages of operation of the damper between its two extreme positions. 45 Further and more specific aims of the invention are to provide a mechanism therefor that is economical of construction and manufacture, and which is durable and dependable.

The above named objects, as well as other purposes which will appear as the specification of my invention proceeds, are accomplished by, and my invention is exemplified in the preferred form of embodiment which is described in the following specification and is illustrated in the accompanying drawings,

Suitable characters of reference identify the several parts of the invention as they appearin the different views in the drawings, in which Figure 1 is a side view of my invention, -a portion of the fan casing, and a portion of the entry box being broken away.

Figure 2 is' a front view, taken in the direction of arrow 4 in Figure 1.

Figure 3 is a top plan view of Figure 2.

Figure 4 is a vertical cross section view on the line 4-4 as seen in the direction of arrow 4 in Figure 1.

Figure 5 is a vertical cross section view on the line 5-5 as seen in the direction of arrow 4. in

Figure 1.

Figure 6 is a detached cross section detail view taken on the line 6--6 in Figure 4, enlarged.

Figure 7 is an enlarged vertical central longitudinal sectional view on the line 'l1, in the direction of arrow! in Figure 3.

Figure 8 is a front view of Figure 7, the cam carrier member being partly broken away.

Figure 9 is a rear view of Figure 8, a portion of the disk-shaped damper plate being broken away.

Figure 10 is a top plan view of Figure 8. Figure 11 is a vertical cross section view on the line ll-|l in Figure '7.

Figure 12 is a front view of the invention taken in the direction of arrow 4 in Figure 1, there being embodied in this view in Figure 12, a modification whereby the damper may be operated by mechanical means.

The fan casing A and fan wheel B are of usual construction, the casing having a central opening C through which the air and gas are admitted. Conduit D which is attached to the discharge mouth of the casing, extends to the burner (not shown). At the said opening C, I provide a chamber like receptacle which I designate as an entry box I. This entry box communicates at its open side 2 with the opening C of the fan casing. Provided in the opposite side 3 of said box, are spaced segmental air inlets 4. A plate 5 which is secured by suitable cap screws constitutes a closure of the bottom of the entry box, and it also constitutes the base of a housing 6. In a threaded aperture in said plate 5 is secured a fuel gas supply pipe 5a. A fluted flanged valve head 8 which is retained loosely in a bore in the rear wall of said housing and is seated as at 9 has a stein ID that is received in the central bore of an abutinent head II. This abutment head is screwed to securely sealed position in the front wall of said housing. A helical spring l2 whose one end bears against the shank of said abutment head,

has its other end bearing against the said valve head 8, the latter being thereby retained yieldingly in its position, as shown in Figure 7.

Pivotally fulorumed on a supporting post I4, is a lever I5 whose lower and rounded end i6 impinges against the face of the valve head 8. The power arm of said lever has the rounded face w Slidingly retained in the longitudinal bore of a bushing I! that is securely seated in a bore l8 of a lug provided on the interior of the box wall, is a push rod 20. This push rod made preferably of non-corrosive material, is of such length that with its inner end at engagement withthe face l6 of the said lever, its other end extends beyond the face of the entry box. p I v I Retained loosely in the said bore 8, is a ring made of fiber or other suitable material, and which I designate as a brake member 2|. cal spring 22 which is disposed within said bore |8 urges the said brake member forwardly as indicated in Figure 6. The function of this brake member will be presently referred to.

A shaft 24 which is secured to and which proiects from the wall 3 of the entry box is threaded at its end, and it supports the parts to be presently referred to. r

A device which I designate as a damper, consists of a metal disk 26 having its rear face machined to bear directly in engagement with the machined front face of the wall 3 0f the entry box; In this disk are provided spaced portways 21 which correspond in shape and dimension with the air inlets 4'of the entry box, and an arcuate slot 28 positioned between said portways is so spaced from the center of the disk that the end portion of the push rod 20, is received therein. The said disk, provided with a suitable boxing29 is journaled on the shaft 24, as shown in Figure '7. At the top surface of the entry box, as shown in Figures 3 and 10, and spaced from right to left, are index characters which may be desig-- nated as stations 7, 6, 5, 4, 3, 2, l, and 0. An index tooth finger 30 on the peripheral face of the disk 26 is so positioned with reference to the portways 21 that when they are in registration with the air inlets 4, as shown in Figure 2, the said finger 30 is in registration with the station 7.

In a shallow recess 3| provided therefor at the rear side of said disk, (see Figure 9) an arcuate strip 32 of resilient material, preferably strip steel, has its shank portion secured to said disk as by cap screws 33. This strip is of a length to span the slot 28 and its urge is toward the front face of the disk. Projecting from the front of the disk, and spaced from the hub thereof, as shown in Figures 7 and .8, is a stud 34. A segmental carrier plate 35 provided with an aperture in which the said stud 34 is received, is secured to the said disk by means such as cap screws 36.

On a curve having a radius the same as the slot 2-8,, threaded adjusting pins 38 are arranged in successive order, asshown in Figures 2 and 8, and they are designated by numerals, reading right to left, namely 0,, 1, 2, 3, 4, 5, :6, and '7. Each of these pins is individually adjustable by the use of a suitable implement such as a screw driver. The adjusting :of these threaded pins being toward or from the cam strip 32, the outside boundary line of the said cam strip, ac-

cordingly is defined, and it is determined by the positions to which these several individual pins are adjusted. Against the said cam strip 32, the push and 2|! impinges, and to which further reference will presently be made.

To facilitate the moving of the said disk I pro- A helivide a crank 40 whose body portion 4|, provided with a suitable flanged boxing 42, is journaled on the shaft 24. In the said body portion 4| is a recess 43 in which the stud 34 is received. By a binding nut 45 and washer 46, the said crank and the aforesaid disk are retained in operative position on the shaft 24, as shown in Figure 7. The th of the push rod 20 is such that when the disk is in the position shown, the portways 21 of said disk being in registration with the air inlets 4 and the indicating finger 30 being in registration with station '7, see Figure 7, the gas valve 8 is in the open position. Pressure of the spring 22 against thebrake member 2| holds the latter firmly against the rear surface of the disk 26', thereby holding the disk against becoming dislodged from any of the positions to which it may be set.

For the maintaining of a fuel mixture that is of proper-consistency for the demands due to different furnace capacities, conditions, and requirements, my invention is entirely effective.

In the set-up shown herein, air inlets 4 are wide open when the index finger 30 is, at 7 stat on, Gas valve 8 is in open position. By the pressure of spring 12, transmitted through valve head 8, and lever l5, to push rod 20, the latter is urge in the direction of arrow in Figure 7, and it is held impinged against the cam strip 32.

Preliminary o operating the apparatus, the arm 40 is moved in the direction of arrow 01f theindex finger 39 being brought to registro tion with station 0. The air inlets 4 now are closed. The pin 0 is now in such position that the valve 8 is in closed position. Arm 4!) is now moved in the direction of arrow On, bringing index finger 30 to station 1. r The fan is put into operation. Pin 1 is then adjusted so to afiord the desired measure of opening at valve 8. When tests .at the furnace (not shown) indicate that the proper amount of gas has been obtained with relation to the amount of air admitted by the air inlet 4 (at the stage wherein finger 3|] is at size..- tion 1) the arm. 40 is again moved in the direc-. tion of arrow On, bringing the index lingo 0 to station 2. Pin 2 is then adjusted so as to offord the desired measur of pening at valve 8. When tests at the furnace show that the proper ratio of gas to the air as admitted by the air inlet 4 is had, (at stage wherein finger 3|] is at station 2), the arm 40 is again moved in the direc ion of arrow on, the finger 30 p ssing from sta ion to station 3. Pin 3 is then adjusted as above 1 5 scribed, and in the further successive movement of the disk, its index finger is at th st tions o 4, 4 to .5, 5 to 6, and 6 to '7, pins .3, 4i and 7, are adjusted as above described.

It will be understood that after the several pins 38 have been adjusted as aforesaid, the :contour line of the cam strip 32 is subject to variations in degree accordingly. It is for the rQaSQn that the amount of gas required, with relation to the amount of .air admitted, must be modified conformity with the demands incid n "to arbitr ry requirements at the furnace, that I hav provided the cam which is capable of being made into contour necessary to obtain variation of the position of the valve 8.

It will be understood that by the pressure of spring 42, the push rod 20 is at a l tim in p needagainst the face of th cam str and that the action of the latter, in causin th waive head to function when the said d sk i moved, is positive, direct, and dependable.

By my invention and its operation as abpye gelscribed, it is possible to obtain an air and fuel gas mixture wherein there is a modification of the variation of the amount of fuel gas, with relation to the amount of air being admitted to the fan, at each of the several stations at which the index finger of the damper is set during the operating of the damper from the completely off position to the completely on position.

Another advantage of my invention is, that it lends itself to e-flicient use in instances where it is desired that the damper may be operated by mechanical means. For an installation intended as above, no change is made, except that a crank member of the construction, as shown in Figure 12, and designated by the numeral 50, is substituted for the crank member 40. In the body portion 5! of this crank 50, are opposed spaced concentric slots 52, in which are retained knuckle studs 53 and 54 which are capable of being made fast at desired difierent adjusted positions in said slots.

For example, the damper is to be so operated that its cycle will be only between the station 0 and the station 4. The said studs 53 and 54 are so positioned, that with the indicator finger 30, at station 4, the arm 59 is at the lowermost point of its stroke. Now with the swing upwardly of the said arm 50, the hub or body portion 5| idles until knuckle 53 meets the stud 34 and thence the carrier member 35 and the cam 32 is moved in the direction of the arrow marked Off, until finger 30 meets the station 0 (the top limit of the stroke of said arm 55). As the arm returns to lower position, the knuckle 53 leaves stud 34 and later, the knuckle 55 meeting the stud 34 carries the cam in the reverse direction and to its original position, namely station 4. Means for mechanically actuating the arm 5! as above described, may consist of an electric motor 55 which is mounted upon the entry box I. Power transmitting connections may consist of the crank 51, and the connecting rod 58, one revolution of the said crank 5'! imparting to the arm 59 a raising and lowering motion.

In the embodiment of my invention as it is 11- lustrated herein, the amount of machine work involved is relatively small, the difierent parts are capable of being economically assembled, and the apparatus in its entirety is close-built and substantial, and not liable to become deranged or to get out of order. Access may be readily had to the interior thereof when necessary for inspection, or for renewals, and the device throughout is capable of being adjusted to meet the most thereof communicating with the air inlet of the fan, a valve in the said entry box and which is retained yieldingly in closed position, a fuel gas supply pipe to said valve, a damper adapted to vary the area of said entry box air inlets, a push rod mechanism adapted to move the aforesaid valve to open position, a resilient cam strip carried by the damper and in engagement with said push rod mechanism, and spaced pins on said damper and in registration with said cam strip and which are individually adjustable to modify the outside boundary line of said cam strip.

2. A gas mixing apparatus comprising a fan whose casing is provided with an air inlet opening, an entry box having an open side communicating with said air inlet opening and having air inlets through its opposite side, a valve in said entry box and which is retained yieldingly in closed position, a fuel-gas supply pipe connected to said valve, adamper movable rotatively to vary the area of said air inlets, means to move said valve to open position, and a cam carried by said damper to actuate said valve moving means, the said cam being capable of adjustment whereby the degree of opening and closing of the gas valve is varied in conformity with the degree of opening and closing of the said air inlets during all stages of operating the damper from the fully open, to the completely closed position.

3. A gas mixing apparatus comprising a fan whose casing is provided with an air inlet opening, an entry box having an open side communicating with said air inlet opening and having air inlets through its opposite side, a valve in said entry box and which is retained yieldingly in closed position, a fuel-gas supply pipe connected to said valve, a disk-shaped damper movable rotatively to vary the area of said air inlet, and a cam carried by said damper to actuate the said valve moving means, the said cam being capable of modification at different stages of the cycle of operating of the damper between its extreme positions.

4. A gas mixing apparatus comprising a fan whose casing is provided with an air inlet, an entry box having an open side communicating with said air inlet and having air inlets entering same, a valve in said box and which is retained yieldingly in closed position, a fuel-gas supply pipe connected to said valve, a disk-shaped damper movable rotatively to vary the area of said air inlets, a push rod mechanism in the entry box and which is operable to move said valve to open position, a resilient cam strip carried by the damper and in engagement with said push rod mechanism, and spaced pins arranged on said damper and in registration with said cam, and which are adjustable to modify the outside boundary line of said cam strip at the different stages of the movement of the damper between its extreme positions.

JOHN J. MAXON. 

